Alarm-bell mechanism for an alarm timepiece



May 7, 1968 JEAN-CLAUDE SCHNEIDER 3,331,466

"BELI MECHANISM FOR AN ALARM TIMEPIECE ALARM 4 Sheets-Sheet 1 Filed Oct.4, 1965 JEAN'CLAUDE SCHNEIDER 3,381,466

BELL MECHANISM FOR AN ALARM TIMEPIECE May 7, 1968 ALARM- Filed Oct. 4,1965 4 Sheets-Sheet 2 JEAN-CLAUDE SCHNEIDER 3,381,466

ALARM-BELL MECHANISM FDR AN ALARM TIMEPIECE Filed Oct. 4, 1965 May 7,1968 4 Sheets-Sheet 5 May 7, 1968 JEAN-CLAUDE SCHNEIDER ALARM-BELLMECHANISM FOR AN ALARM TIMEPIECE 4 Sheets-Sheet 4 Filed Oct. 4, 1965United States Patent 3,381,466 ALARM-BELL MECHANISM FOR AN ALARMTIMEPIECE Jean-Claude Schneider, La Chaux-de-Fonds, Switzerland,assignor to Fabrique dHorlogerie Chs. Tissot et Fils S.A., Le Locle,Neuchatel, Switzerland, organized under the laws of Switzerland FiledOct. 4, 1965, Ser. No. 492,384 Claims priority, application Switzerland,Oct. 9, 1964, 13,130/64; Sept. 8, 1965, 12,516/65 15 Claims. (Cl. 58-16)In alarm timepieces, the alarm-bell mechanism generally comprises analarm-bell wheel provided with ratchet teeth driving the hammer. Thelatter is secured to an escapement comprising two projections whichslide altenratively on the inclined flanks of the teeth of thealarm-bell wheel when the latter is freed, in such manner that thehammer oscillates and strikes the bell.

According to the present invention we provide an alarm-bell mechanismfor an alarm timepiece comprising an alarm-bell provided with teeth, aspring for the en tr'ainment of the alarm-bell wheel and an oscillatingescapement provided with an impulsion member for urging an oscillatinghammer from an equilibrium position, an input projection and an outputprojection, the said projections engaging alternately in the teeth ofthe alarmbell wheel, the input projection locking the wheel whereas theoutput projection is urged out by the teeth thereof, the hammer beingarranged to return to its equilibrium position, the hammer striking abell in the course of its oscillation.

The accompanying drawings show, by way of example, two embodiments ofthe mechanism according to the invention.

FIGURE 1 is a plan view of the first embodiment in a first operatingposition,

FIGURE 2 is a similar view in a second operating position,

FIGURE 3 is a view in partial section of the mechanism shown in FIGURES1 and 2,

FIGURE 4 is a partial plan view of the second form of embodiment, and

FIGURE 5 is a view in section along the line VV of FIGURE 4.

The mechanism shown in the drawings is intended to be lodged in a smallalarm clock provided with a circular bell 1 and in its upper portion,with a rod 2 for stopping the ringing action, the rod being verticallymovable and adapted to be displaced into different positions, as will beexplained later. A hammer 3 having the form of an arc of a circle issuspended within the bell 1 for free pivoting about a horizontal arbor4. In the inoperative position, its center of gravity is located in avertical plane extending through the axis of the arbor 4. Thus, thehammer occupies a position of equilibrium in which one of its endscontacts the bell 1.

An alarm-bell wheel 5 secured to a driving pinion 6 is driven inrotation in the clockwise direction seen in FIG- URE 1, when thealarm-bell mechanism is tripped. To this end, the pinion 6 engages witha wheel 7 which turns through rather less than a complete rotationduring the unloading of an alarm spring 8. FIGURE 3 shows that the wheel7 is mounted idly on an arbor 9 and has Breguet form teeth on its upperface. These teeth mesh with corresponding teeth 10a formed in the lowerface of a cam .11 to which the inner end of the spring 8 is attached.The outer end of the said spring is secured to 'a post 12 which isattached to a frame element 13. The cam 11 rotates clockwise during theloading of the alarm spring and anti-clockwise during the unloadingthereof, the Breguet coupling 10 being designed in such manner that thewheel 7 is entrained only during the unloading. The cam 11 is keyed tothe arbor 9, by means of a central aperturehaving a rectilinear edgeco-operating with a corresponding flat 14 on the arbor 9. The latter isdriven in rotation during the loading period by means which are notdescribed and is then freed at the instant of tripping of the alarmmechanism. It then rotates in the anti-clockwise direction as seen inFIGURE 1.

In order to drive the hammer 3, the mechanism comprises an escapement 15which pivots on a pin 16 secured to a frame element 17. The escapementhas two projections .18 and 19 which co-operate with the teeth of thewheel 5 in the manner of the pins on a conventional escapement. Theprojeceion 19 constitutes an input projection which, when it is engagedin the teeth of the wheel 5 locks it, whereas the projection 18constitutes an output projection which, when it is engaged in the teethof the wheel 5, is expelled therefrom whilst rocking the escapement 15.A stud 20, constituting an impulsion member and fixed in the escapementopposite the projections 18 and 19 then communicates a pulse to thehammer 3.

FIGURE 1 shows, in broken lines the position into which the hammer 3rises under the effect of the impulses of the escapement. When removedfrom its position of equilibrium, it drops back under the effect of itsown weight and the front edge of the 'arm of the hammer brings about, atthe end of travel, the disengagement of the escapement which recoversthe position shown in FIGURE 1, at the same time, the hammer 3 strikesthe hell 1.

Instead of the hammer oscillating freely when it receives the impulsefrom the escapement, it may also be braked, and then recalled by aresilient element 21 which consists of a rectilinear arm of a wirespring wound about a cylindrical post 22 on the frame element 13. Thesaid wire spring is normally in the position shown in full lines ofFIGURE 1. However, it can be displaced into the position 21' shown inbroken lines, in which case it bears constantly against a stud 23 fixedin the arm of the hammer. It is clear that the wire spring, in itsposition 21, is loaded as soon as the impulse is imparted to the hammer,in such manner that the latter ascends to a lower level than when it isfree and the disengagement of the escapement 15 is brought about morerapidly. The striking rate is thus accelerated. This variation in thestriking rate may be obtained automatically during the alarm-bell actiondue to a rocker 24 consisting of a thin blade pivoting on a stud 25.Fixed in the said rocker are two parallel pins 26 which embrace the limb21 of the wire spring at a point very near the post 22.

A rotation of the rocker 24 in the clockwise direction sulfices todisplace the wire spring from the position 21 to the position 21. Thisrotation is brought about by the cam 11. The latter has in its upperface a series of grooves 27, 28 and 29. Furthermore, the rocker 24 has,at its lower part, an arm at the end of which is secured a pin 30 which,in the position shown in FIGURE 1, is engaged in the groove 27. Therocker 24 is resilient, in such manner that the pin 30 bears slightlyagainst the bottom of i 3 the groove 27. The resilience of the rocker 24permits furthermore displacements of the cam 11 in the axial directionwhen it is entrained clockwise during windingup, the Breguet coupling10, 10a being freed.

As will be seen in FIGURE 1, the grooves 27, 28 and 29 have a V-shapedprofile. They extend in concentric arcs of a circle centred on the axisof the arbor 9. The grooves 27 and 29 extend in an arc of substantially330. The groove 28 comprises two segments 28 and 28a and begins in thegroove 27 at approximately 80 from its commencement. It extends along achord of a circle having its centre on the axis of the arbor 9 then hasa portion comprising an arc of a circle centred on the axis of the arbor9, and then a second portion on the chord by means of which it reachesthe groove 27. The segment 28a also commences in the groove 27. It has arectilinear chordal portion and a portion forming an arc of a circlecentred on the axis of the arbor 9. The ends of the grooves 27. 28a and29 are joined by a radial groove 31. At the commencement of the alarmaction, the cam 11 is in the position shown in FIGURE 1. If the pin 30is in the inlet of the groove 27, the rocker being in a positionillustrated in FIGURE 1, it will be seen that the cam 11 maintains thesaid rocker immobile for as long as the pin is in the groove 27. At theinlet of the groove 28, the pin is drawn towards the axis of the arbor9, thus pivoting the rocker 24 clockwise and displacing the resilientwire 21 into the position 21'. From this instant on, the hammer rate isaccelerated. 7

When the pin follows the portion of the groove 28 approaching the groove27, the rocker pivots anti-clockwise and the pins 26 return theresilient wire 21 into its normal position. The rate of the hammer isslowed down once more. The same phenomenon of acceleration of the rateis reproduced when the pin 36 reaches the groove 28a.

It will be noted that the device described also comprises a mechanism(not shown) which brings about the momentary stopping of the rotation ofthe cam 11 and of the wheel 7 at the instant at which the pin leaves thegroove 28 to return into the groove 27, in such manner that theactuation of the alarm mechanism, when it takes place as describedhereinabove, is eifected in two stages which may follow each other withan interval of greater or lesser length and each of which comprises aslow-rate period and a rapid rate period.

The rocker 24 further comprises an arm 32 extending in the direction ofthe axis of the hammer and having an abutment face 33 at its free end.In the position illustrated in FIGURE 1, the said abutment face 33 isdisposed in such manner that the stud 23 of the hammer reaches a pointvery near this face at the instant at which the hammer impinges againstthe bell. In this position, the face of the abutment 33 is thusinactive. It is also inactive when the rocker has pivoted towards theright so as to accelerate the hammer movement. On the contrary, itbecomes active if the rocker pivots anti-clockwise out of the positionshown in FIGURE 1 and passes into the position shown in FIGURE 8. Theabutment 33 then locks the hammer 3 in a raised position, spaced-apartfrom the bell 1. n

the other hand, the studs 26 remove the wire spring 21 from the stud 23but bring up a further resilient element consisting of a shorter arm 34of the wire spring 21 contacting a stud 35 projecting from theprojection 19 of the escapement 15. The resilient arm 34, under theseconditions, causes disengagement of the escapement. The wheel is able torotate clockwise and the escapement 15 oscillates regularly without thehammer being actuated. Ifreference is again made to FIGURE 1, it will beseen that it suflices to pivot the rocker in such manner that the pin 30passes from the groove 27 or from the groove 28 to the groove 29, so asto put the mechanism in the position illustrated in FIGURE 2. Thealarm-bell movement then develops idly until the pin 30 reaches theheight of the groove 31 (FIGURE 2).

In this position, the alarm-bell mechanism is stopped.

Furthermore, the weight of the hammer 3 exerted through intermediary ofthe stud 23 on the rocker 24 pivots the latter clockwise, the pin 30sliding in the groove 31, and the rocker returns into therapid-operation position. A winding-up mechanism then entrains the cam11 in the clockwise direction and restores it finally to the startingposition shown in FIGURE 1.

The passage of the pin from the groove 27 to the groove 29 may bemanually controlled, at will. For this purpose, the rocker 24 has athird arm 38 terminating in an abutment face 36 extending under thecontrol rod 2. The lower end of the said rod extends normally to aheight such that the abutment 36 just contacts it when the rocker is inthe rapid-operation position. In the slowoperation position, a smallspace therefore extends between the rod 2 and the abutment 36 (positionshown in full lines in FIGURE 1). However, a pressure may be exerted onthe rod 2 at any desired instant and it causes the rocker to pass fromone of the two operating positions into the idle-travel position. Therod 2 is carried on an annular member provided with an abutment whichcan be screwed into a support on the time-piece. By screwing thissupport, it is possible to displace the lower end of the rod 2 into theposition shown in broken lines in FIGURE 1. It will be seen that therocking of the rocker 24 in the clockwise direction at the instant ofpassage of the pin 30 at the inlet of the groove 28 is then prevented bythis rod.

The inclined flank of the groove 28 passing through the groove 27 atthis point tends to entrain the pin 30 toward the axis of the arbor 9,but since the rocker is prevented from pivoting, the pin 30 ascends thesaid oblique flank and drops back into the groove 27. The samephenomenon takes place when the groove 28 reaches the groove 27 and atthe commencement of the groove 28a. In other words, by screwing thesupport of the knob 2, the rocker is compelled to remain constantly inthe slow-operation position.

No acceleration of the rate'of the hammer during the ringing action isproduced.

The screwed or unscrewed position of the support of the knob 2 does notof course have any influence on the pivoting of the rocker whichdisplaces the pin in the groove 29. In other words, the knob forstopping the ringing action, on the rod 2 may be actuated whatever theposition of the support. On thecontrary, if the latter is in the screwedposition, the pin 30, instead of sliding in the groove 31 as far as theinlet of the groove 28a, at the end of the ringing action, will onlyslide as far as a point opposite the end of the groove 27. For thispurpose, an inclined ramp 37 is formed at the outlet of the said groove,so as to permit the pin to enter it readily at the instant of winding-upof the alarm-bell mechanism. The cam 11 could also have only two groovesinstead of three, if no variation in the operational rate is desired. Itcould also have only a single groove 28 instead of two grooves 28 and28a, so as to produce only one variation in the striking rate during thecomplete ringing action.

Furthermore, the mechanism described could also be utilised with adevice for winding'up the alarm-bell action which differs from thatshown in the drawings.

The projections on the escapement could be inverted, in such manner thatthe inlet projection provides the impulse and the outlet projectionserves as an abutment.

The alarm-bell mechanism shown in FIGURES '4 and 5 is similar, in broadoutline, to that of FIGURES'I to 3. It comprises an alarm-bell wheel 40which is capable of rotating in the direction of the arrow 41 under the'action of an alarm-bell spring (not shown), an escapement consisting ofthe two members 42 and 43 and a hammer 44 actuated by the escapement.

The main element 42 of the escapement is mounted on a pivot rod 45(FIGURE 5) which is secured at its lower end in a boss 46 forming a partof a frame element of the alarm mechanism. The element 42 has a stud 47projecting from its upper face coaxially with the rod 45 and terminatingin a pivot 48 of reduced diameter, which is freely engaged in a seatingformed in a frame element located immediately above the escapement. Theelement 43 is mounted on the stud 47. It comprises a sleeve portion 49which guides it relatively to the stud 47. As can be seen from FIGURE 4,the element 43 forms the input projection 50 of the escapement whereasthe element 42 forms, at one of its ends, the output projection 51. Thislatter member is prolonged beyond the pivoting point of the escapementin the form of an arm one of the sides 52 of which cooperates with thestud projecting from the hammer 44. The member 42 has furthermore alateral finger 53 forming, with the side 52, a notch in which aprojection portion 54 of the member 43 is engaged. The portion 54 limitsthe possible angular movement between the two elements of theescapement.

In order to improve the cooperation between the teeth 55 of the alarmmechanism wheel 40 and the projections 50 and 51 on the escapement, thelatter each have a rectilinear side 56, 57 and the teeth 55 each have aplane, oblique face 58 extending from their apex in the direction of thearrow 41.

The improvement in the functioning obtained due to the specialconstruction of the escapement as just described results, on the onehand, from the fact that the members 42 and 43 which carry the entry andoutlet projections are articulated relatively to each other and, on theother hand, from the fact that the teeth of the alarm mechanism wheelare able to act by communicating an impulse to the outlet projection 51during the time that the sides 58 of the said teeth slide on the tip ofthe projection.

During the impulse, i.e. during the time that a tooth 55 bears on theside 56 of the projection 51 and the side 52 of the escapement urges thehammer 44, the member 43 only begins to engage in the teeth of the wheel40 when its stud 54 contacts the side 52 of the member 42. The depth ofpenetration of the said projection is thus diminished. Furthermore, theaction of the face 58 on the teeth 55 on the tip of the projection 51prolongs the impulse to the maximum extent.

On the contrary, during the return movement of the hammer, when thelatter rocks the member 42, by bearing on the side 52, the member 43which contacts a tooth 55 and retains the alarm mechanism wheel remainsimmobile until the finger 53 entrains it by contacting the stud 54. Theangular travel of the two parts of the escapement therefore retards thedisengagement to the maximum extent. The penetration of the outletprojection in the teeth may be increased in such manner that the impulsecommences as soon as the disengagement has terminated, i.e. as soon asthe tip of the projection 50 has reached the front end of the face 58 ofthe tooth which it retains.

The mechanism of FIGURES 4 and 5 permits an improvement in theefiiciency of the escapement by approximately 30% relative to thearrangement of FIGURES 1 to 3.

It will be noted furthermore that the rocker provided for modifying thefunctioning conditions of the escapement and the spring adapted to beput into contact with one of the projections on the escapement so as topermit the rotation of the alarm mechanism wheel when the hammer isimmobilised, have not been shown.

I claim:

1. An alarm bell actuating mechanism comprising:

an alarm bell wheel provided with teeth;

an alarm spring for entraining the alarm bell wheel;

an oscillating hammer adapted to strike the bell in the course of itsoscillation, said hammer having an equilibrium position and beingarranged to return to its equilibrium position;

an oscillating escapememnt having an input projection and an outputprojection, said input and output projection alternately engaging theteeth of the alarm bell wheel, said output projection being located atthe trailing side of the escapement with respect to the direction ofrotation of the alarm bell wheel and being shaped so as to lock saidwheel when it en-, gages the teeth thereof, said input projection beinglocated at the leading side of said escapement with respect to thedirection of rotation of the alarm bell wheel, said input projectionbeing urged out of said wheel when it engages the teeth thereof wherebysaid escapement will rotate in a first direction;

a driving member mounted on said escapement, said driving membercontacting said hammer and urging the hammer from its equilibriumposition when said escapement oscillates in said first direction, saidoscillation in said first direction causing said output projection tolock in engagement with the teeth on said alarm bell wheel, return ofsaid hammer to its equilibrium position urging said output projectionout of engagement with the teeth of said alarm bell wheel and permittingsaid hammer to strike the bell.

2. A mechanism according to claim 1, wherein the hammer is caused toreturn to its equilibrium position by a horizontal pivot.

3. A mechanism according to claim 1 wherein the hammer is caused toreturn to its equilibrium postiion by resilient element loaded by thehammer when the latter moves away from the equilibrium position, in onedirection.

4. A mechanism according to claim 3, wherein the said resilient elementis adjustable between two positions in one of which it remainsconstantly out of contact with the hammer whereas in the other it isloaded with each oscillation of the hammer.

'5. A mechanism according to claim 4, wherein the resilient element iscontrolled by a rocker.

6. A mechanism according to claim 5, wherein the said rocker comprises asensing means co-operating with a guide element driven in rotationsimultaneously with the alarm-bell wheel, the said guide element beingdisposed in such manner as to bring about a rotation of the rocker andthe displacement of the resilient element from one of the said positionsto the other during the ringing action.

7. A mechanism according to claim 3, wherein a second adjustableresilient element is provided, which is adapted to be displaced to aposition wherein it co-operates with the escapement so as to bring aboutthe disengagement thereof without the intervention of the hammer.

8. A mechanism according to claim 7, wherein the second resilientelement is also controlled by the rocker and the latter has an abutmentwhich, in the position wherein the second resilient element co-operateswith the escapement, locks the hammer.

9. A mechanism according to claim 8, wherein the rocker furthercomprises an arm for manual control permitting the rocker and the secondresilient element to be selectively disposed in the position for rockingthe hammer.

10. A mechanism according to claim 1 wherein the escapement comprisestwo members which are articulated to each other and which are capable ofmoving through a limited angle relatively to each other, each of themhaving one of the projections.

11. A mechanism according to claim 10, wherein the output projection hasa rectilinear side along which the teeth of the alarm-bell wheel areable to slide so as to impart to the escapement an impulse to actuatethe hammer.

12. A mechanism according to claim 10 wherein the teeth of thealarm-bell wheel have an oblique face co-operating with the outputprojection in such manner as to prolong the duration of the impulseuntil the rear end of the said oblique face leaves the tip of theprojection.

13. A mechanism according to claim 10, wherein the articulation pivotbetween the two said members coincides with the pivoting axis of theescapement.

14. A mechanism according to claim 10, wherein the member which carriesthe output projection is secured to 7 an arm extending beyond theescapement pivoting point References Cited and carrying the said impulsemember. UNITED STATES PATENTS 15. A mechanism according to claim 10,wherein one 720 801 2/1903 Hauser 5821 12 l of the sad membersconstituting the escapement has :1 15911081 11/1928 Pierce 58 21.12

projecting portion and the other a recess the dimensions 5 of which arelarger than those of the said projecting por- RICHARD B. WILKINSON,Primary Examiner. tion, the latter being engaged in the recess in suchmanner as to limit the angular displacements of the two members GERALDBAKER Exammer' relatively to each other. M. LORCH, EDITH C. SIMMONS,Assistant Examiners.

1. AN ALARM BELL ACTUATING MECHANISM COMPRISING: AN ALARM BELL WHEELPROVIDED WITH TEETH; AN ALARM SPRING FOR ENTRAINING THE ALARM BELLWHEEL; AN OSCILLATING HAMMER ADAPTED TO STRIKE THE BELL IN THE COURSE OFITS OSCILLATION, SAID HAMMER HAVING AN EQUILIBRIUM POSITION AND BEINGARRANGED TO RETURN TO ITS EQUILIBRIUM POSITION; AN OSCILLATINGESCAPEMENT HAVING AN INPUT PROJECTION AND AN OUTPUT PROJECTION, SAIDINPUT AND OUTPUT PROJECTION ALTERNATELY ENGAGING THE TEETH OF THE ALARMBELL WHEEL, SAID OUTPUT PROJECTION BEING LOCATED AT THE TRAILING SIDE OFTHE ESCAPEMENT WITH RESPECT TO THE DIRECTION OF ROTATION OF THE ALARMBELL WHEEL AND BEING SHAPED SO AS TO LOCK SAID WHEEL WHEN IT ENGAGES THETEETH THEREOF, SAID INPUT PROJECTION BEING LOCATED AT THE LEADING SIDEOF SAID ESCAPEMENT WITH RESPECT TO THE DIRECTION OF ROTATION OF THEALARM BELL WHEEL, SAID INPUT PROJECTION BEING URGED OUT OF SAID WHEELWHEN IT ENGAGES THE TEETH THEREOF WHERBY SAID ESCAPEMENT WILL ROTATE INA FIRST DIRECTION; A DRIVING MEMBER MOUNTED ON SAID ESCAPEMENT, SAIDDRIVING MEMBER CONTACTING SAID HAMMER AND URGING